Conventionally, in a continuous assemblage of pots for raising and transplanting seedlings, individual square or hexagonal tubular pots are formed by expanding papers or paper-like tin films and linked by link pieces to form continuous piece. The continuous assemblage of pots for raising and transplanting seedlings is made by overlapping the continuous pieces and using a water-soluble adhesive to attach the overlapping continuous pieces to one another. (For example, refer Patent Document 1). This kind of continuous assemblage of pots for raising and transplanting seedlings is kept in a flattened state while in storage and expanded when in use, forming a honeycomb assembly of tightly grouped individual pots. Numbers of seedlings can be intensively cultivated, by filling the individual pots with cultivation soil and sowing the seeds. Also, in the continuous assemblage of puts for raising and transplanting seedlings, the water-soluble adhesive is degraded by watering wile the seedlings are being raised, and after the seedlings have been raised for a specified number of days, the overlapping continuous pieces can be separated and pulled apart in sequence by pulling on one end. For example, as described in Patent Document 2, it is possible to plant the seedlings efficiently by using a simple planter that rests on the ground.
Incidentally, in the conventional continuous assemblage of (hexagonal tubular) pots as described above, because it is necessary to group the individual pots tightly, the length of a link piece is arranged as the same length as a side face of an individual pot. When the seedlings are planted continuously by using a simple planter as described in Patent Document 2, the space between a neighboring plant is restricted by the length of the link piece, so cases occur in which the interval between the planted seedlings is too short for the crop for which the seedlings are cultivated, so that the use of the continuous assemblage of pots for raising and transplanting seedlings must be abandoned.
Therefore, in Patent Document 3, for example, a continuous assemblage of pots is disclosed, in which an extension portion, that is longer than a side face of an individual pot is provided to a link piece. The extension portions are folded and attached to one another with a water-soluble adhesive, and either a front or a rear side of each extension portion is attached to a side face of each individual pot with a water-soluble adhesive. Also, in Patent Document 4, a continuous assemblage of pots is disclosed, in which slits of a predetermined length are provided to a link piece or to an individual pot, allowing the link pieces to be extended through the slits.
However, the continuous assemblage of (hexagonal tubular) pots that is disclosed in Patent Document 3 has a problem, in that, the water does not penetrate sufficiently thorough the folded portions of the extension portions of the link pieces, and the water-soluble adhesive is not degraded sufficiently while raising the seedlings, so that the folded portions of the link pieces do not stretch and separate smoothly during the raising, leading to dispersion in the lengths of the link pieces, that is, in the intervals between the planted seedlings. Another problem is that, not only must the extension portions of the link pieces be folded and attached to one another with the adhesive, but the folded portions must also be attached to the individual pots, complicating the manufacturing process and increasing the cost. Yet, another problem of the continuous assemblage of pots as disclosed in Patent Document 4, is that, when the individual pots are pulled apart in sequence for transplanting, stress of the pulling force is concentrated at the end of the slit portion, easily breaking the continuous assemblage of pots.    Patent Document 1: Japanese Patent Publication JP S58-11817    Patent Document 2: Japanese Patent Publication JP H05-308822    Patent Document 3: Japanese Patent Publication JP H08-205687    Patent Document 4: Japanese Patent Publication JP H07-123869